The present disclosure relates to a light source apparatus and a projector utilizing this light source apparatus.
In recent years, techniques with the use of a laser light source as a light source of a projector have been proposed. Japanese Patent Application Laid-open No. 2012-3042 (hereinafter referred to as Patent Document 1) proposes the way of using laser light, which is coherent light emitted from a laser light source, by scattering the laser light by a scattering element in which a fluorescent material is mixed. In this light source apparatus, while reducing coherency of the laser light to reduce speckle noise in the outgoing light, it is possible to reproduce the color of the image by combining the luminescent colors of both the laser light itself and the fluorescence emitted from the scattering element excited by the laser light (see, for example, paragraph [0018] of Patent Document 1, etc.).
As the light source apparatus of Patent Document 1 uses fluorescence, which is randomly-polarized (as in the state of natural light, with its polarization direction being random) light whose optical loss tends to be large, it is configured to arrange the polarization directions of the fluorescence to be the same direction using a polarization conversion element, in order to enhance the utilization efficiency of light. The polarization conversion element has a polarizing beam splitter, a reflecting mirror and a polarization rotation element. The light that was incident on the polarizing beam splitter is emitted branched into two optical paths, by being isolated into a polarization component in a first polarization direction (p-polarization component) and a polarization component in a second polarization direction orthogonal thereto (s-polarization component). The polarization rotation element provided in one of the two optical paths causes the polarization plane of light to be rotated by 90°. By the reflecting mirror and the like, the two optical paths are directed to an exit surface of the polarization conversion element in parallel. Thus, one light beam incident on the polarizing beam splitter is allowed to be emitted being converted into two light beams having the same single polarization component.